Airplane propeller deicer shoe



I Aug 7, 1945. R. W.'BROWN 2,381,381

I AIRPLANE PROPELLER DEICER SHOE I Filed June 11, 1941 a Sheets-Sheet 1 Jvvuwwlm PoY W. Bnowra R. w. BROWN AIRPLANE PROPELLER DEICER SHOE .Aug. 1, 1945.

Filed June 11, 1941 3 Sheets-Sheet 2 lli RoY W. bRowN Aug. 7, 1945. fR. wJamowN 2,381,381

AIRPLANE PROPELLER DEICER SHOE Filed; June 1;, 1941 s Sheets-Sheet :s v

Patented Aug. 7, 1945 AIRPL E PROPELLER. DEICER SHOE I Roy W. Brown, Akron, Ohio, assignor to The Firestone Tire & Rubber Company, Akron, Ohio, I [a corporation of Ohio Application June 11, 1941; Serial No; 397,650

' 3 Claims; (01144-139 g This invention relates to airplane propeller deicers generally, especially to an improved deicer shoe, method. of attaching thedeicer shoe, and the means used in the attaching operation.

-- It obviously is necessary to-secure very tight and thorough adhesion between the deicer shoe {and the propeller'bl'ade due to the severe air stresses to whichv the deicer-shoe is subjected, since; such pressures would tear the shoe from .the'propellerunless uniform and complete adhesion is obtained The adhesion problem in- 'v olved is complicated by the irregular and varied contoifrs of propellers. Such contoured surfaces are dimcultto ,work with in that it is hard to j obtaina uniform pressure when applying the deicer shoe to the propeller. I pne problem'involved in attaching deicer shoes to airplanes in service is that the propeller usually have; to be removed from the airplane before attaching the deicer shoes thereto. As it takes several hours both to remove a propeller from an airplane and to reassemble it, such removal is objectionable and it is highly desirable to secure thedeicer shoev to the propeller while same is on 'theplane.

' In the typesof deicer shoes now in service,

some diiliculty is encountered in retaining deicer fluid inthe deicer shoe until suchfluid is moved 7 radially outwardly of the propeller th'e desired ilistance. V Y r Y v p r s The general object of the present invention is fto. provide a novel, improved deicer shoe and to provide an improved method of assembling such -a'shoeon'apropeller; s r v N Another oblect of the invention is to provide a deicer shoe which is better adapted to retain deicer fluid-therein while enabling such fluid to move radially outwardly. of the propeller. I

v Further objects, of. theinv'ention are to provide improved means for securingdeicer shoes toprope lers; to provide arapid'; inexpensive'method for securing deicer shoes to airplane propellers even though such propellers are mounted on an air- 7 plane; and to provide, a. deicer shoe which is 1 molded to such acontouras to facilitate mounting same on the leading edge of a. propeller.

The foregoing and further objects will be manifest as, the specificationproceeds, the specification being described with particular reference to the accompanying drawin s in which:

Figure I is an elevation oi a propeller; having a deicer'shoe of the-invention secured thereto; I Figure Ills an elevation of a propeller showing glue siebp inth'e process of securing the deicer shoe ere v V v e Figure Ill is anenlarged fragmentary sectional elevation taken on line IIIe-IH. of Figure II;

Figure IV' is a plan of a deicer shoe'embodying the invention;

Figure V is a sectional elevation taken on line V-V of Figure IV;

Figure VI is a plan of pressure apparatus used in securing a deicer shoe to a propeller; I

Figure VII is a sectional elevation taken on line VII-VII of Figure VI; I I

Figure VIII is a sectional elevation showing the manner in-which the pressure bag of Figure VI is secured to propeller;

Figure IX is a prospective view further illustrating the manner in which the pressure bag is secured to a propeller;

Figure X is an elevation of another embodiment of heating and pressure apparatus of the invention showing it attached to an airplane propeller on an airplane;

Figure XI is an enlarged perspective view, parts ly in section, or -the propeller of Figure X; and

Figure XII is a detail section of the connecting g means for the pressure bag.

Referring in detail to Figure I of the drawings, a propeller ID of standard construction isshown therein. This propeller I0 is carried on a hub II propeller H], which shoes I! are usually formed from rubber, or'synthetic rubber, but other rubber-like, or plastic substances may be used when l suitable. The deicer shoes ii are initially molded so that they are substantially inverted V shape in section, as shown in Figure V to facilitate mounting them on the leading edge of a propeller. The deicer shoes have tapered edges so that they can be secured to a', propeller having a desired airfoil contour without materially changing same. Of course, the deicer'sh'oes I 2 may be positioned in recessed regions of the propeller ill. but the shoes are so thin that they do not materially interfere with the air flow characteristics of apropeller that has been entirely preformed before securing the deicer shoe thereto. V

Figure IV best shows that the plurality of longitudinally extending grooves [3 are formedin the deicer shoe I! at the'base or hub end thereof. One groove Ila is centrally positioned in-and extends the length of the deicer shoe while theremaining grooves are formed in'corresponding positions on opposite sides; of the central groove connected to the central groove |3a by angularly positioned grooves l4, each of which extends between the end of one of the grooves I3 and connects it to the groove |3a. Note that the grooves H are so positioned that the grooves from corresponding grooves l3 on opposite sides of the groove |3a do not intersect the groove |3a at the same place but that such points of intersection are slightly spaced. The grooves l3and |4 all have parallel edges or side walls, as initially molded. However, when the deicer shoe is secured to the propeller; III, which has a substantially cylindrical hub portion, the deicer'shoe is flattened out in the portion thereof overlying the cylindrical portion of the propeller 1.. By such flattening out of the inverted V shape deicer shoe, the central groove |3a thereof has its side walls pivoted inwardly towards each other from the base of the groove so that the walls converge toward their upper edges. The converging walls of the groove |3a adjacentthe hub otjghe propeller greatly facilitate retention of deicer, fluid in the groove while still permitting ready radial movement thereof. As the propeller, from the propeller hub radially outwardly, progressively becomes blade-like with its leading edge becoming relatively sharp it will be seen that as the edge of the blade'becomes sharper the shoe applied thereto becomes'flattened less, until a point is reached where the sides of the V-shaped shoe will be drawn toward each other when the shoe is applied to the propeller as illustrated in Fig. II. While the walls of the central groove |3a will converge toward their .upper edges at the hub portion of the propellen'it will now be. seen that this convergence progressively changes into divergence as the leading. edge of the propeller becomes sharper than the V, shape of the shoe. A sump, or liquid collecting recess I5 is formed in the hub end of the deicer shoe, l2 and in operation suitable means (not shown) are associated with the propeller for depositing deicer fluid into the sump. Centrifugal force then moves the deicer fluid radially through the grooves l3 and |3a so that the deicing action is exerted, over the lengthof the deicer shoe and overthe surface of the propeller when the fluid spills out of the Ordinarily the'deicer shoes |2 are best applied to the propeller by cementing them thereto. A rubber cement, which is compounded so as to secure rubber-to-metal adhesion, is applied to the leading edges of the propeller HI. Then the premolded deicer shoe I2 is applied to the cemented leading edge of the propeller at the hub end thereof and gradually stitched or pressed into engagement with the propeller, as indicated in Figure II. Note that the initial contour of the shoe |2 facilitates its engagement with the propeller. After the deicer shoe I2 is stitched into as tight engagement with the propeller as is possible, then a pressure boot 2| is secured to the propeller. Thev pressure boot 2| comprises an outer flexible but inextensible layer, usually madefrom rubberized fabric 22 and an inner layer or surface of electroconductiverubber 23. The edges of the electroconductive rubber 23 may be reinforced by rubberized fabric 24. The electroconductive rubber has an air tight chamber 25 formed therein, which chamber extends the length of the pressure boot 2| ,or only the edges of-the electroconductive 7 rubber 23 are secured to the rubberized fabric layer 22 to forma chamber therebetween. Note that a plurality of apertured rivets 23 are secured to the'longitudinally extending edges of the boo 2| to facilitate securing same to a propeller, or other contoured surface with which it is to be used. The electroconductive rubber 23 has longi- -tudinal1y extending electric conductors 21 embedded therein, in order to set up anelectrical potential within the rubber. Socket means 28 are connected to eachof the conductors 21 at one end thereof and are integrally bonded to the pressure boot 2| whereby suitable sources of electrical energy can be connected to the pressure boot. A valve 23 also is secured to the pressure boot and [v connects to the chamber 25 through a conduit 3| formed in the pressure boot. In use of the pressure boot 2|, a cord 32, or other desired element, is threaded through the rivets 26 in the opposite edges of the pressure boot and then the cord 32 is tightened in order to secure the flexible pressure boot to the irregular and varied contour of the propeller. After the pressure boot is v brought into as tight engagement with the pro- -peller as is possible, then the compartment is inflated as shown in Figure VIII in order to force the electroconductive rubber 23 tightly and uniformly against the deicer shoe l2 and force it 25 tightly against the propeller. Then suitable electric conductors 33 and 34 are connected to the 1 sockets 28 and electric current is passed through the electroconductive rubber 23, which is compounded in any suitable manner to facilitate passage of current thereto. -This flow of electricity 7 through therubberheats same to a relatively high temperature, such as 90 to 100 C. and this heat, being in immediate contact iwth the deicer shoe 1,2, acts to dry, polymerize, and/or vulcanize 3 the cement applied to the propeller and secure a permanent bond between the deicer shoe and the propeller. Theheating definitely speeds up the drying of the'cement which usually is wet when the shoe is applied.

Figure X illustrates the manner in which modified heatin and pressure apparatus of the invention are used. In this instance, a triblade propeller 4| is mounted on an airplane 42 and a deicer shoe |2a is to be secured to the leading pedge of one blade of the propeller 4|. An inflatable, flat, pressure bag 43, usually made from rubber, or rubberized fabric, is secured to the propeller 4| by a strip 44 of any suitable wrapping material. The bag 43 has integral, longitudinally extending ribs 45 formed thereon at the edges thereof and the strip 44 bears against them to press the bag tightlyagainst the shoe |2a and it, in turn, against the propeller 4|. Tubular valve stems 48 are integrally securedto the bag 43 adjacent the corners thereof, which stems extend into the bag and connect to the chamber .therein. A portable electric boiler 41 is connected to the bag 43 by flexible conduits 48, 48 extending from the upper end of the boiler and by conduits 49, 49 extending from the lower end of the chamber. The conduits 48 connect to the steam chamber of the boiler, while the conduits 49 connect to the liquid collecting zone of the boiler. Then steam is introduced into the bag 43 by conduits 48, which are connected to the upper end of the bag, and condensate, or cooled steam is withdrawn from the bag by conduits 49. In order to build up pressurein the bag 49 .7 and control flow of steam therethrough, a thermostat. 5| is associated with the boiler. The thermostat is connected in lead 53 of the leads 53 and 54 thatnsupply the'boiler 41' with electrical energy. The thermostat 5| turns .on and Shu s off the electric supply and thus maintains practice has required varied contour of a paratus disclosed thesteam pressure and temperature within the pressure bag 43 to the desired values.

The conduits l8 and l! are connectedto the valve' stems 45 by fittings 55 that slip there around. The fittings 55 include tubes '56, which extend into the conduits. and which line up with holes 51 formed in the sides of the valve stems 48. Castle nuts 58 e age with the ends of the I valve stems and secure the fittings in position by i forcing them against the bag.

The boiler 41 may be merelysuspencled from the propeller, or it may be supported on the ground but, in all events, the boiler and pressure bag are a readily portable complete unit for adhering deicer shoes to airplanes.

By practice of the invention a deicer shoe can be secured to an airplane propeller, when it is on a plane, in an hour or two whereas previous from the plane; ltiwill be apparent that the to secure a deicershoe thereto but that the apherein overcomes this difficulty.

It will be seen that the means used to' apply a deicer shoe to a propeller are small, light, weight, and easily handled, so that they can be transported readily. Hence such means can be used to. secures. deicer shoe to an airplane propeller'while it is mounted upon an airplane. Then too, the contour of the deicer shoe is such that it adapts itself readily'to the engagement with the leading edge of a propeller and this also facilitates mounting same under tions. V It will be appreciated that the pressure bags 2| andand the therewith, are interchangeable, and also that the adverse condiseparate features of such apparatus, as the ribs ,also may be used on the other pressure bag.

48 hours to effect adhesion and has also required removing the propeller propeller makes it dimcult ings.

Whatis'claimed is: v

1. In a propeller construction, a propeller having a cylindrical hub, a rubber deicer shoe which is molded to substantially inverted v shapein section secured to the leading edge of said pro peller andextending radiallyoutwardly from the hub thereof, said shoe having a longitudinally extending, centrally positioned parallel walled groove formed in its outer surface, said shoe be ing flattened out in the portion thereof adjacent said hub whereby the walls of said groove converge. towards their outer edges and facilitate retention of deicer fluid therein while enabling radially outward movement thereof.

2. In a propeller construction, a propeller having a hub, a rubber deicer shoe which is molded to substantially inverted V-shape in section secured to the leading edge of said propeller adjacent the hub thereof, said shoe having a longitudinally extending parallel walled groove formed in its outer surface, said shoe being flattened out in the portion thereof adjacent said hub whereby the walls of said groove converge towards their outer ends and facilitate retention of deicer fluid therein. 1

3. A deicer shoe comprising anelongated, thin rubber body having a longitudinally extending heating means associated groove formed in its outer surface, which groove is positioned along thecenter line of said body and has side walls that converge toward their outer edges.

, I, ROY W. BROWN. 

